Tap grinding fixture



Oct. 25, 1949. w. J. LUSK TAP GRINDING FIXTURE Filed Aug. 22, 1947Patented Oct. 25, 1949 UN?! TED .S TATES PATENT s-FICE TAP -GRINDINGFIXTURE WilliamaLLusk, Ber-ea, Ohio Application August'22, 1947, SerialNo. 740,121

2-Claims. 1

This invention relates to grinding m'a'chines and to fixtures adapted.fbl supporting taps and similar devices during the grindingpperat'i-on.

An object of the invention is to vprovide:aftap grinding fixture whichis 'adaptetl to support :a tap in position to be operated upon by :a.gsrinding wheel and the like.

Another object of the invention-is to provide a tap "grinding fixtureadapted to reclaim ldmll or broken tape by cutting offfithe end andregrinding with the proper lead and taper.

A further object of the invention is to provide a tap grinding fixtureincorporating easily acljustable means for :regrin'ding taps with two orfour flutes es the-case may be.

Still another object of the invention is to rovide-atop grindinglilxturewhich is simple'in de sign, inexpensive to manufacture, and which iseffective in operation and quickly and easilyadiustable for the*grinding operat-ion, andrthen easily releasable for removing the tapthereafter.

Otherobiects and advantages of the invention will become apparent from'the following description of a preferred embodiment thereof-asillustrated in the accompanying drawing, and in which:

Figure l isa right end elevationof the device shown inFigure 1.

Figure 2 is a longitudinal sectional elevation of my improved tapgrinding fixture, taken on line 2-2 of Figure '1.

Figure 3 is an elevationaldetail view of the tap gripping colletemployed in the device, shown separately.

In the regrinding of broken or worn taps, it is :2

spiral flutes therein, two or four flutes being ground in as the casemay be. The present application discloses means for accomplishing thiseasily and efficiently.

In order to understand clearly the nature of the invention and the bestmeans for carrying it out, reference may now be had to the drawings, inwhich like numerals denote similar parts throughout the several views.

As shown, there is a fixture body indicated generally at [0 andincluding a hollow cylindrical housing l2 supported upon a base [4 byupright leg-like members I6, all formed or cast as an integral unit. Anopening I8 is thus formed in the space between the leg members l6,affording access to the middle portion of the fiat top sur- .2 face 26,thus permitting 'a single bolt to be inserted through the vertical bore2 2 in the basetfor single bolt mounting thereof.

The base of the .fix'ture thus clamps securely to the grinding tableinpositionfor cooperation with the grinding wheel usually :also carriedthereby. A longitudinal bore :24 :is .formed 'in the "cylindricalhousing l2 to receive the outer cylindrical sleeve 26, the sleevebeingithus turna-ble about its axis within the housing bore. The outersleeve 26 is provided'at one end with an annular lintegral collar1or.1'-lange.'28 one radial wall of which abuts against the 'outer endof the cylindrical housing 1-2.

annular retaining collar :36 encircles the opposite end of the outersleeve :26, thus serving to retain the outer sleeve in position againstdisplacement from the bore 24. .An --eccentriclongttudinal bore 34 is.formed inth'eoute-r sleeve 26.. its "eccentricity being best shown inFigure :1, to receive an inner sleeve 32 which is similarly providedwith an outer flange-=36 abutting against the end surface of the outersleeve 26.

As-seen'loestin Figure 2, the inner :sleeve32 extends wholly through theouter sleeve .26, their left :hand eends being co extensive .and-.secured together by means of a set screw :38 extending through aradial :bore 40 formed through the overlying outer sleeve and collar 36the inner end of the screw extending into the annular groove 39.

The rotary travel of the :outerisleeve 26 i's'c'ontrolled by a radial-handle*4"ll the shank'of which extends through an rarcuate motionlimiting 'slot 42 formed in the housing 42, the :inner end :of thehandle shank being threaded :into a radi'al .bore 44 fformed in thesleeve -26. v.'Ihe'=o1'1ter:sleeve also has a positioning pin assemblyindicated generally at 44. The assembly 44 is disposed in a radial bore46 formed in the flange 28 of the outer sleeve, and includes a plungershaft 48 the outer end of which has an integral knob 50 and the innerportion of which extends through the radial bore 46, being almost aslarge in diameter as the I; bore 46 at its inner end.

The reduced shank of the shaft 48 extends slidably through the axialbore in a nut or plug 52 which is threaded into the enlarged outer endof the radial bore 46. A spring 54 encircles the inner portion of theshank of the shaft 48 between the enlarged plunger portion thereof andthe nut 52, thus biasing the plunger portion of the shaft 48 radiallyinwards toward the outer surface of the inner sleeve 32. Under thisbiasing influence, the positioning plunger 48 is thus 3 pressed into anySelected one of four radial recesses 56 which are formed in the outersurface of the inner sleeve 32, and are spaced from each other by ninetydegrees.

The positioning knob 50 is pulled radially outward and the parts turnedto bring the bore 46 into registry with any selected positioning recess56, the knob 50 then being released to allow the spring to press theplunger into the underlying recess 56. The set screw 38 is thentightened so its inner end presses firmly into the annular turned groove39, holding the parts securely in position.

The inner sleeve 32 has an axial bore 60 extending longitudinallytherethrough to receive a collet tightening shaft or draw bar 62 to theouter left hand end of which is secured a turning knob 64 whereby theshaft may be turned. The right hand end of the axial bore 60 is enlargedto receive the shank of a collet 66 having jaws 68 adapted to receivetherebetween the shank of a tap to be ground. It will be seen that theright hand end of the shaft 62 is threaded into the left hand end of thecollet shank so that upon turning the knob 64 the collet is drawn in aleftward direction to press its gripping jaws toward each other underthe camming influence of the cam surfaces 68 of the collet. The tap isthus held securely in the collet in this manner.

To use the fixture, the tap to be ground is inserted in the collet 66and tightened by means of the draw bar 62. Thereafter the position pin48 is used to position the tap for either two or four fiutes as the casemay be, and the handle 40 is turned within the limits of the-slot 42each time the tap is positioned by pin 48, the grinding wheel thusoperating upon selected flutes on the tap.

Although I have described a preferred embodiment of my invention inspecific terms, it is to be understood that various changes may be madein size, shape, materials and arrangement without departing from thespirit and scope of the invention as claimed.

I claim:

1. A workholder for supporting a workpiece for limited eccentric rockingmovement about a longitudinal axis, said workholder comprising a base,said base having a longitudinal tubular housing having a concentricbore, an outer tubular cylinder rotatably fitting said concentric bore,said outer cylinder having a bore parallel to but eccentric with respectto said concentric bore, an inner cylinder rotatably fitting saideccentric bore, means preventing sidewise movement of said outer andinner cylinders and said housing relative to each other, a workpiececlamping collet arranged to project axially from one end of said innercylinder, indexing means operating between 4 said outer and innercylinders for releasably holding said inner cylinder in any one of anumber of different predetermined positions of rotation of said innercylinder relative to said outer cylinder, and handle means on said outercylinder arranged for rotating said outer cylinder relative to saidcylindrical housing, said positions of rotation of said inner cylinderrelative to said outer cylinder being equally circumferentially spacedfrom each otherfand means on said cylindrical housing limiting the swingof said handle means in either direction to a circumferential distanceequal to the distance between adjacent ones of said positions ofrotation.

2. A workholder for supporting a workpiece for limited eccentric rockingmovement about a longitudinal axis, said workholder comprising a base,said base having a longitudinal tubular housing having a concentricbore, an outer tubular cylinder rotatably fitting said concentric bore,said outer cylinder having a bore parallel to but eccentric with respectto said concentric bore, an inner cylinder rotatably fitting saideccentric bore, means preventing sidewise movement of said outer andinner cylinders and said housing relative to each other, a workpiececlamping collet arranged to project axially from one end of said innercylinder, indexing means operating be tween said outer and innercylinders for releasably holding said inner cylinder in any one of anumber of different predetermined positions of rotation of said innercylinder relative to said outer cylinder, and handle means onsaid outercylinder arranged for rotating said outer cylinder relative to saidcylindrical housing, said positions of rotation being equallycircumferentially spaced, said handle comprising a radial arm fixed toproject from said outer cylinder, said cylindrical housing being formedwith-a circun-iferentially extending slot passing said arm and of alength to limit the swing of said handle arm in either direction to adistance equal to the distance between any two adjacent positions ofrotation of said inner cylinder.

WILLIAM J. LUSK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Dawson Dec. 31, 1946

